Research On Dual-Motor Drive Control Based On EtherCAT Real-Time Industrial Ethernet

Horizontal telescope generally use the single motor to drive the pitch axis,with the increment of telescope diameter,the single motor haven't met the system requirements because of its limitations,therefore we consider using dual motors to drive the shaft.In this paper,the corresponding dual motor drive control system is built by means of real-time industrial Ethernet EtherCAT technology.Taking advantage of high real-time and synchronization accuracy of the outstanding performance in EtherCAT,the accurate synchronization between the two motors can be ensured.Based on KingStar Motion software from Interval Zero Corporation,the EtherCAT master station function was developed.The AxN servo drive was used as the slave.The experimental platform was built to test the performance of the dual motor control.Firstly,the limitations of the single-motor drive control of the large-diameter telescope pitch shaft system are introduced,which leads to the synchronous control of the dual motors.In order to ensure the real-time and synchronization of the communication in multi-motor control system,the industrial Ethernet technology is put out.Among them,EtherCAT,which proposed by Beckhoff Company in Germany,has been widely used and developed rapidly for its superior performance.By comparing and analyzing a variety of real-time industrial Ethernet,it is clear that EtherCAT can be effectively applied to multi-motor synchronous control system.Secondly,the EtherCAT technology is studied in depth,including its communication principle and system composition,physical transmission medium,frame structure definition,message addressing mode,communication service command of master station operating station,distributed clock synchronization mechanism,communication mode and so on.Thirdly,a motor drive control system based on EtherCAT real-time communication is designed.The thesis focus on how to use KingStar Motion software to achieve PC-based EtherCAT master function,a brief description of how the AxN is configured as an EtherCAT slave is given.The Ether CAT master and slave communication program design is described in details.A single motor closed-loop test was carried out to verify the feasibility of the system.Finally,the dual motor drive control system based on EtherCAT is implemented on the basis of single motor drive control.A variety of dual motor synchronous control strategies are introduced,experiments were performed to compare their respective tracking and synchronization performance.The experimental analysis of single motor drive control and dual motors drive control is also carried out,which clarify the advantages of dual motors drive control.